Forecasting Terminology

The most common terms used for weather forecasts, describing the duration, distribution and probability of occurrence of rainfall.

For Duration of Rainfall

  • Brief - short, sudden showers or periods of rain

  • Intermittent - on and off intervals, not continuous

  • Occasional - irregular, infrequent intervals of precipitation

  • Frequent - persistent short intervals, happening regularly and often

  • Periods of precipitation - rain or snow falling most of the time with breaks

For Distribution of rainfall

  • Isolated - showers separated during a given period of time

  • Few - indicated in time, not over an area

  • Local - restricted to a smaller area

  • Patchy - irregularly occurring in an area

  • Scattered - not widespread but of greater occurrence than isolated showers

  • Widespread – covering wide area, nearly 75%

  • Fairly Widespread – covering all area, almost 100%.

For Probability of Occurrence of Rainfall

Probability of occurrence



Could Occur


May Occur


Would Occur


Will Occur


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